The throttle valve, which is slidably movable in a bore, regulates the flow of transmission oil through the transmission's valve body. A linkage couples the position of the accelerator pedal to the throttle valve, and causes the throttle valve to move between an idle or low throttle position and a full or wide open throttle position. Throttle valve controlled transmissions utilize a cable running from the vehicle's fuel management system whether a fuel injector or carburetor to the transmission's valve body. The cable linkage between a modern fuel injector/carburetor system provides a signal method for proper transmission function. The cable connection is commonly known as the throttle valve (TV) cable. The TV cable connects the throttle mechanism to the transmission hydraulic control valve. The throttle valve reciprocates in a common bore in the transmission valve body, and is typically composed of a plunger, spring, and throttle valve. The positioned relationship of these components determines how the transmission will operate.
The TV cable is used to connect the carburetor linkage at one end, to a swinging lever at the other end. The swinging lever moves the throttle valve. Any movements of the carburetor linkage, during normal driving, results in a corresponding movement of the TV cable. Carburetors have a range of movement from idle to wide open throttle (W.O.T.). As normal carburetor linkage movement pulls the TV cable, the swinging lever rotates thereby pushing the throttle valve plunger down its bore. This plunger has a designed operating range from its engineered starting point to a fully inwardly depressed position, wherein the range of motion is specific to a particular make and model. Even slight movement of the throttle valve linkage results in a corresponding movement of the throttle valve. As the throttle valve moves, it will adjust the shift timing, feel, and firmness of the transmission.
For the throttle valve system to function properly, actuation of the throttle valve must be proper for the particular vehicle. Just because the plunger (and therefore the TV) is mechanically made to move through its engineered spectrum of movement, does not mean the transmission will perform in the desired manner. The rate of movement at any given point can be altered by the dynamics of the carburetor linkage, and can dramatically affect transmission performance characteristics. When new cars are designed, the correct linkage relationship is established for each particular vehicle. This is done to satisfy the different transmission operating responses needed for the different types of vehicles. For example, a luxury car's TV system is not designed the same way as a performance car's TV system, nor as a pickup truck's TV system.
Mechanisms for controlling transmission throttle valves are well known in the art. For example, U.S. Pat. No. 4,631,983 shows a lever mechanism for a cable linkage including a control lever mounted on a rotary shaft for rotation therewith, a base plate mounted on the rotary shaft and fixed to the control lever for rotation therewith, and a lever plate adjustably assembled with the base plate and connected at one side of its outer peripheral portion to one end of the cable linkage. The lever plate is provided at its outer peripheral portion with a semicircular guide surface having a center located substantially at a rotation fulcrum of the lever plate. The cable linkage is supported on the semicircular guide surface of the lever plate. And the lever plate is displaceable on the base plate. During the assembly process, the distance between the semicircular guide surface and the rotation fulcrum is adjustable. U.S. Pat. No. 4,711,140 illustrates an improved throttle valve regulating system for automatic transmissions for motor vehicles. The throttle valve reciprocates in a bore as a result of the action of a plunger and a throttle valve spring to control the flow and pressure of transmission fluid or oil to effect gear shifting. A rigid spacing element of predetermined length received within the throttle valve spring is provided for urging the valve towards a full throttle position in the event that the valve sticks in the bore in a lower throttle position. The system further includes a high rate spring located in the full throttle position in the bore to prevent sticking of the valve in that position, and a low rate spring similarly positioned in the bore to counteract the force of the throttle valve spring for returning the throttle valve to a low throttle or zero position. The reciprocating throttle valve includes at least one land or circumferential flange having sharpened edges for shearing large particles or other impurities introduced into the bore with the transmission fluid which might otherwise become wedged between the valve and the bore and cause sticking of the valve in a fixed position in the bore.
U.S. Pat. No. 5,046,380 defines a throttle valve operating cam of an automatic transmission and an output control member of an automotive engine that are interconnected so as to cooperate with each other by a cable consisting of an outer tube and an inner cable. The inner cable is connected to the throttle valve operating cam and the output control member. One end of the outer tube is connected first to the automatic transmission. The other end of the outer tube is regulated in position relative to a cable fitting member secured to the automotive engine and then fixed to the cable fitting member secured to the automotive engine.
U.S. Pat. No. 5,727,425 comprises a method for adjusting the throttle valve cable in an automatic transmission. In a motor vehicle automatic transmission, for example a GENERAL MOTORS THM 700-R4 automatic transmission, the TV cable forms part of the mechanical link between the throttle pedal, the throttle valve linkage on a fuel delivery system (e.g., a carburetor or electronic fuel injector), and the throttle valve. The TV cable is adjusted using a sleeve and spring installed at the distal end of the TV cable between the cable end clamp and a teardrop shaped cable end fitting on the TV cable. The spring opposes the movement of the cable end fitting toward the distal end of the TV cable so that the cable end fitting is at its maximum distal position only at fully open throttle. This gives the vehicle operator the shift feel of a shorter TV cable at most throttle openings. The sleeve and spring are installed only on TV cables in automatic transmissions that do not have TV cable end fittings permanently attached to a throttle cam.
Providing a system which pulls the TV cable the correct distance while the carburetor linkage rotates from engine idle to wide open throttle is a relatively simple engineering exercise. However, just because the TV cable provides the correct cable pull distance as the linkage rotates from idle to wide open throttle does not automatically mean the transmission will behave correctly or appropriately. For example, because a transmission performs a second gear to first gear downshift doesn't mean it will do so at the appropriate time or with the correct firmness. The real issue is “behavior”. To further exacerbate the situation, each individual driver defines what he or she believes is proper and correct behavior. Vehicles receiving these transmissions can vary tremendously from one another. Many of these differences can have an effect on the behavior of a transmission. A few factors which effect transmission performance are (1) more or less powerful engines, (2) vehicles of different weights, and (3) tires sizes and rear end ratios.
In view of the above, a method is needed for providing the required TV cable pull distance and allowing adjustment of the rate of cable pull. The present invention accomplishes this by always providing the correct cable pull distance, and by also allowing the installer to quickly adjust the rate of TV cable pull per degree of carburetor linkage rotation.